1. Field
The present invention relates to an operation control apparatus and method thereof for a commutatorless motor, and more particularly to an operation control apparatus and method thereof for an the commutatorless motor by which the current can flow in at least one of the windings during drive of the commutatorless motor to thereby maintain large torque.
2. Description of the Related Art
Generally, a DC motor is smaller in size and has a higher operating efficiency than an AC motor and is known to have a capacity of continuously variable operation.
However, a brush is used in the DC motor as a switching means in order to supply a DC power source to a rotor, and in case the brush is used, there have been generated disadvantages in that frictional loss resulting from mechanical contacts and the like has occurred.
Therefore, in order to cope with the disadvantages, a commutatorless motor is disclosed, replacing the mechanical switching means with an electronic switching means, which is much applied to various appliances such as a refrigerator, air conditioner and the like,
FIG. 1 is a schematic block diagram for illustrating an operation control apparatus of a conventional commutatorless motor, where an operation control apparatus of a commutatorless motor having a two-phase stator winding is disclosed by way of example.
As illustrated in FIG. 1, the operation control apparatus of a conventional commutatorless motor comprises: a rotor position detecting unit 10 for detecting a rotor position in the commutatorless rotor 70; a frequency dividing unit 20 for dividing a pulse signal supplied from the rotor position detecting unit 10; a first pulse distribution unit 30 for utilizing the pulse signal from the frequency dividing unit 20 to thereafter generate n pulse signals having a predetermined phase difference; a revolution establishing unit 50 for generating pulse signals for controlling a revolution of the commutatorless motor according to the pulse signal of the rotor position detecting unit 10; a second pulse distribution unit 40 for utilizing the pulse signals from the first pulse distribution unit 30 to thereafter generate 2n pulse signals and for determining an activated time of each phase field coil of the commutatorless motor 70 according to signals from the pulse signals and from the revolution establishing unit 50; and a switching unit 60 for being operated by the signals output from the second pulse distribution unit 40 to thereafter drive the commutatorless motor 70.
Meanwhile, although not illustrated, a mark corresponding to "1" or "2" in a binary code is attached on each pole, by way of example, the N pole and S pole, of the rotor in the commutatorless motor 70.
In the foregoing structure, the rotor position detecting unit 10 comprises a Hall Sensor and the frequency dividing unit 20 comprises a flip-flop.
FIG. 2 is an output waveform diagram of major parts in the apparatus illustrated in FIG. 1, wherein FIG. 2a is a waveform diagram for illustrating the commutatorless motor 70 rotating at a low speed and FIG. 2b is a waveform diagram for illustrating the commutatorless motor 70 rotating at a high speed.
In FIGS. 2a and 2b, illustrations are drawn to have the same pulse width for the convenience sake.
First of all, FIG. 2a illustrates a pulse waveform detected by the rotor position detecting unit 10 according as the rotor of the commutatorless motor 70 rotates.
The pulse is input to the dividing circuit unit 20 and the revolution establishing unit 50.
The frequency dividing unit unit 20 divides the waveform to thereafter output a pulse as illustrated in FIG. 2b.
The pulse is input to the first pulse distribution circuit 30. The first pulse distribution unit 30 utilizes the pulse, thereby generating a pulse having a predetermined phase difference.
The pulse is illustrated in FIG. 2c.
The first pulse distribution unit 30 outputs the pulse and a pulse as illustrated in FIG. 2b, which are input to the second pulse distribution unit 40, which generates a pulse having a predetermined phase difference by utilizing the aforementioned pulses.
The pulse are illustrated in FIGS. 2d and 2e.
Meanwhile, the revolution establishing unit 50 receives pulses as illustrated in FIG. 2a output from the rotor position detecting unit 10, thereby outputting two pulses for controlling the speed of the commutatorless motor.
In other words, the revolution establishing unit 50 generates a pulse which drops at a falling edge (as illustrated in FIG. 2a) and rises after lapse of a predetermined time t1 to thereafter maintain a high level for a predetermined time T1 (as illustrated in FIG. 2f), and generates a pulse which drops at a rising edge (as illustrated in FIG. 2a) and rises after lapse of the predetermined time t2 to thereafter maintain a high level for the predetermined time T2 (as illustrated in FIG. 2g).
The pulse generated at the revolution establishing unit 50 is input to the second pulse distribution unit 40.
The second pulse distribution unit 40 logically multiplies the pulse generated at the revolution establishing unit 50 by the pulses illustrated in FIGS. 2b, c, d and e to thereafter output the same.
In other words, the pulse in FIG. 2b is logically multiplied by the pulse in FIG. 2f, the pulse in FIG. 2c logically multiplied by the pulse in FIG. 2f, the pulse in FIG. 2b logically multiplied by the pulse FIG. 2g and the pulse in FIG. 2c logically multiplied by the pulse in FIG. 2g, to thereafter output the pulses as illustrated in FIGS. 2h, i, j and k, which are all input to the switching unit 60.
The switching unit 60 generally comprises transistors (not shown) and the transistors are turned on when the pulses in FIGS. 2h, i, j and k are in high levels, whereas the current flows in the windings of the commutatorless motor 70.
At this time, rotating speed of the commutatorless motor 70 is enabled by varying low level or high level time (t1) (t2) a (T1) (T2) of the pulses output from the revolution establishing unit 50 as illustrated in FIGS. 2f and 2g.
In the operation control apparatus of the conventional commutatorless motor thus constructed, no problem occurs in the case of the rotational speed of the commutatorless motor 70 being at high speed as illustrated in FIG. 2b because the current flows at least in one of the windings. However, a problem occurs in the case of the rotational speed being at low speed as illustrated in FIG. 2a because no current flows in the windings.
In other words, the rotor on the commutatorless motor should be rotated by inertia at a portion where the current does not flow at the winding, which causes a problem in that torque thereof becomes weak.
Accordingly, the present invention has been disclosed to solve the aforementioned problem, and it is an object of the present invention to provide an operation control apparatus of a commutatorless motor by which the current can flow at least in one of the windings for larger torque.
It is another object of the present invention to provide an operation control method of a commutatorless motor by which the current can flow at least in one of the windings for larger torque.
In accordance with one aspect of the present invention, there is provided an operation control apparatus of a commutatorless motor, the apparatus comprising: a rotor position detecting unit for detecting a rotor position of the commutatorless motor; a revolution establishing unit for controlling revolution of the commutatorless motor; a microprocessor for outputting pulse signals for driving the commutatorless motor according to signals output from the rotor position detecting unit and revolution establishing unit while the pulse signals have a predetermined delay time for controlling revolution per minute (RPM) and the delay time has a time for causing the current to flow in another winding before the current flowing in one of the windings of the commutatorless motor is interrupted; and a switching unit for being turned on by the pulse signals output from the microprocessor to thereby cause the current to flow in the windings of the commutatorless motor or to cause the current to stop flowing in the windings for driving of the commutatorless motor.
In accordance with another aspect of the present invention, there is provided an operation control method of the commutatorless motor, the method comprising: a first step for discriminating whether or not the commutatorless motor is driven and for outputting a predetermined initial driving signal according to position of the rotor when the commutatorless motor is under an initial driving state, to thereafter drive the brushless motor; a second step for outputting a driving signal having a predetermined delay time for controlling RPM to thereafter drive the commutatorless motor; third step for controlling the delay time in order to make it possible for the current to flow in another winding before the current flowing in one of the windings on the commutatorless motor operated by the driving signal is interrupted.